........................................................................................................................5 PREFACE ...........................................................................................................................7 ORIGINAL PUBLICATIONS ...............................................................................................9 ABBREVIATIONS ............

Morphological mutants were isolated from a wild strain of Agrobacterium tumefaciens at a high frequency by treatment with a nitrosoguanidine. Seventeen of the 20 mutants isolated were temperature-sensitive. At 27 C, the mutant cells were rod-shaped and at 37 C, spherical or branched, whereas the wild-type cells were rod-shaped at both temperatures.

Agrobacterium overgrowth is a common problem in Agrobacterium-mediated plant transformation. To suppress the Agrobacterium overgrowth, various antibiotics have been used during plant tissue culture steps. The antibiotics are expensive and may adversely affect plant cell differentiation and reduce plant transformation efficiency. The SacB-SacR proteins are toxic to most Agrobacterium tumefaciens...

The thu operon (thuEFGKAB) in Sinorhizobium meliloti codes for transport and utilization functions of the disaccharide trehalose. Sequenced genomes of members of the Rhizobiaceae reveal that some rhizobia and Agrobacterium possess the entire thu operon in similar organizations and that Mesorhizobium loti MAFF303099 lacks the transport (thuEFGK) genes. In this study, we show that this operon is ...

Twenty four diverse cultivars of soybean (Glycine max [L.] Merrill) and three lines of its annual wild progenitor Glycine soja Sieb and Zucc. were tested for their response to Agrobacterium strains harboring either the Ti (tumor-inducing) plasmid (pTi) from Agrobacterium tumefaciens or the Ri (root-inducing) plasmid (pRi) from Agrobacterium rhizogenes following uniform wounding and inoculation....

Agrobacterium tumefaciens and A. rhizogenes transport single-stranded DNA (ssDNA; T-strands) and virulence proteins into plant cells through a type IV secretion system. DNA transfer initiates when VirD2 nicks border sequences in the tumour-inducing plasmid, attaches to the 5' end, and pilots T-strands into plant cells. Agrobacterium tumefaciens translocates ssDNA-binding protein VirE2 into plan...

Agrobacterium tumefaciens is a Gram-negative soil phytopathogenic bacterium that causes the crown gall disease of dicotyledonous plants, which is characterized by a tumorous phenotype. It induces the tumor by transferring a segment of its Ti plasmid DNA (transferred DNA, or T-DNA) into the host genome and genetically transforming the host. One century has past after A. tumefaciens was firstly i...

Luteolin is a phenolic compound from plants that acts as a potent and specific inducer of nodABC gene expression in Rhizobium meliloti. We have found that R. meliloti RCR2011 exhibits positive chemotaxis towards luteolin. A maximum chemotactic response was observed at 10(-8) M. Two closely related flavonoids, naringenin and apigenin, were not chemoattractants. The presence of naringenin but not...

In an effort to identify the Agrobacterium tumefaciens phosphate regulatory gene(s), we isolated a clone from an A. tumefaciens cosmid library that restored regulated alkaline phosphatase activity to an Escherichia coli phoB mutant. The gene that complemented phoB was localized by subcloning and deletion analysis, and the DNA sequence was determined. An open reading frame, denoted chvI, was ide...

The infection of plants by Agrobacterium tumefaciens leads to the formation of crown gall tumors due to the transfer of a nucleoprotein complex into plant cells that is mediated by the virulence (vir) region-encoded transport system (reviewed in [1-5]). In addition, A. tumefaciens secretes the Vir proteins, VirE2 and VirF, directly into plant cells via the same VirB/VirD4 transport system [6], ...